1. Field of the Invention
The invention relates to an integrated memory having memory cells, disposed at intersection points of word lines and bit lines, for storing data bits.
In memories of this type, a number of bits are combined to form bytes and a number of bytes are combined to form a respective word. In this case, a word is the data length of the memory interface, that is to say data having the length of a memory word can simultaneously be written to the memory or read from it.
In graphics applications, a screen may be required to show one and the same color over the whole surface. The screen is allocated an integrated memory whose content is in each case read for the purpose of producing the image on the screen. To show the same color over the whole surface of the screen, the same memory word must be written to all the addresses in the memory. To do this, it is possible to supply the appropriate word to the memory interface continuously and to write it to the whole memory successively by appropriate addressing.
However, in so doing, it may be desirable not to overwrite specific information stored in the memory. In this context, the term used is "masking".
Data sheet MT41LC256k32D4(S) from the company Micron, dated Jul. 1996, pp. 21-23, describes a 256k.times.32 SGRAM (synchronous graphics RAM) which allows byte-wise masking by appropriate masking signals. When a data word is being written, any desired bytes of the word can be masked by the masking signals, so that only the unmasked bytes of the word are written to the corresponding memory cells of the memory.